The present invention relates to a friction gear transmission.
Friction gear transmissions are known in the art. A friction gear transmission can have only one friction point formed by a bevel gear and a friction gear and acting upon a driven shaft. It can also include a doubled friction gear combination which has two friction points relative to a driving face gear on the one hand and relative to a friction gear leading to a driving shaft on the other hand. Each member of this combination is formed as a double member and moved as a whole, for adjusting the transmission ratio, transverse to the transmission axis. In the known friction transmissions of this type, it is known to provide an axial movement of mutually abutting V-shaped curved piece and countercurved piece because of changing torque withdrawal by the consumer. The axial force produced during transmission of the torque in the transmission takes place by the mutually sliding V-shaped curved pieces, when the driving shaft delivers a torque. Changes in the torque delivery, for example because of a consumer-side imbalance, lead to a changes of this axial force, and thereby to an opposite sliding movement of the V-shaped curves against one another. A vibration movemement of the mutually engaging curved pieces takes place. Moreover, this results in a wear at the contact point of the V-shaped pieces, which can lead to a friction corrosion. A lubricating medium introduced between the curved pieces cannot permanently eliminate this danger, inasmuch as the lubricating medium is urged by centrifugal forces during the rotation of the transmission shaft into the outer region of the transmission and therefore is no longer available for lubricating in the region of the V-shaped curved pieces.